Plating method, plating system and storage medium

ABSTRACT

A plating method can improve adhesivity with an underlying layer. The plating method of performing a plating process on a substrate includes forming a first plating layer  23   a  serving as a barrier film on a substrate  2 ; baking the first plating layer  23   a ; forming a second plating layer  23   b  serving as a barrier film; and baking the second plating layer  23   b . A plating layer stacked body  23  serving as a barrier film is formed of the first plating layer  23   a  and the second plating layer  23   b.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a U.S. national phase application under 35 U.S.C. §371 of PCT Application No. PCT/JP2013/054504 filed on Feb. 22, 2013,which claims the benefit of Japanese Patent Application No. 2012-065489filed on Mar. 22, 2012, the entire disclosures of which are incorporatedherein by reference.

TECHNICAL FIELD

The embodiments described herein pertain generally to a plating methodand a plating system of performing a plating process on a substrate, anda storage medium.

BACKGROUND ART

Recently, semiconductor devices such as a LSI or the like have beenrequired to have higher density in order to meet requirements forreducing the mounting space or for improving the processing rate. As anexample of a technology that achieves the high density, there has beenknown a multilayer wiring technology of manufacturing a multilayersubstrate, such as a three-dimensional LSI or the like, by stackingmultiple wiring substrates.

According to the multilayer wiring technology, a through-via-hole, whichpenetrates the wiring substrates and in which a conductive material suchas copper (Cu) is buried, is typically formed in the wiring substrate inorder to obtain electrical connection between the wiring substrates. Asan example of a technology for forming the through-via-hole in which aconductive material is buried, there has been known an electrolessplating method.

As a specific method of producing a wiring substrate, there is known amethod in which a substrate having a recess is prepared, a barrier filmis formed as a Cu diffusion barrier film within the recess of thesubstrate, and a seed film is formed on the barrier film by electrolessCu plating. Thereafter, Cu is buried in the recess by electrolytic Cuplating, and the substrate in which the Cu is buried is then thinned bya polishing method such as chemical mechanical polishing. Through thisprocess, a wiring substrate having a through-via-hole in which the Cu isburied is manufactured.

To form the barrier film of the aforementioned wiring substrate, byadsorbing a catalyst onto the substrate in advance, a catalystadsorption layer is formed, and by performing a plating process on thecatalyst adsorption layer, a barrier film formed of Co—W—B layers isobtained. The barrier film is then baked, so that moisture within thebarrier film is removed and the bond between metals is strengthened.

REFERENCES

Patent Document 1: Japanese Patent Laid-open Publication No. 2010-185113

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

As stated above, the barrier film as the Cu diffusion barrier film isformed through the plating process, and by being baked thereafter,moisture within the barrier film is removed and the bond between themetals is enhanced.

During the baking process, however, a stress may be generated betweenthe barrier film and the substrate, so that adhesivity between thebarrier film and the substrate may be weakened.

In view of the foregoing problems, example embodiments provide a platingmethod and a plating system of forming a barrier film on a substratethrough a plating process and maintaining adhesivity between the barrierfilm and the substrate even when the barrier film is baked, and astorage medium.

Means for Solving the Problems

In one example embodiment, a plating method of performing a platingprocess on a substrate includes a substrate preparing process ofpreparing the substrate; a plating layer forming process of forming aplating layer having a preset function by performing the plating processon the substrate with a plating liquid; and a plating layer bakingprocess of baking the plating layer by heating the substrate. Further,by repeating the plating layer forming process and the plating layerbaking process at least twice, a plating layer stacked body having afirst plating layer obtained through a first plating layer formingprocess and a first plating layer baking process and a second platinglayer obtained through a second plating layer forming process and asecond plating layer baking process is formed.

In another example embodiment, a plating system of performing a platingprocess on a substrate includes a plating layer forming unit configuredto form a plating layer having a preset function by performing theplating process on the substrate with a plating liquid; a plating layerbaking unit configured to bake the plating layer by heating a base; asubstrate transfer unit configured to transfer the substrate between theplating layer forming unit and the plating layer baking unit; and acontroller configured to control the plating layer forming unit, theplating layer baking unit and the substrate transfer unit. Further, byrepeating a plating layer forming process in the plating layer formingunit and a plating layer baking process in the plating layer baking unitat least twice, a plating layer stacked body having a first platinglayer obtained through a first plating layer forming process and a firstplating layer baking process and a second plating layer obtained througha second plating layer forming process and a second plating layer bakingprocess is formed.

In yet another example embodiment, a computer-readable storage mediumhas stored thereon computer-executable instructions that, in response toexecution, cause a plating system to perform a plating method. Further,the plating method includes a substrate preparing process of preparing asubstrate; a plating layer forming process of forming a plating layerhaving a preset function by performing a plating process on thesubstrate with a plating liquid; and a plating layer baking process ofbaking the plating layer by heating the substrate. Furthermore, byrepeating the plating layer forming process and the plating layer bakingprocess at least twice, a plating layer stacked body having a firstplating layer obtained through a first plating layer forming process anda first plating layer baking process and a second plating layer obtainedthrough a second plating layer forming process and a second platinglayer baking process is formed.

Effect of the Invention

In accordance with the example embodiments, a plating layer stackedbody, having a first plating layer obtained through a first platinglayer forming process and a first plating layer baking process and asecond plating layer obtained through a second plating layer formingprocess and a second plating layer baking process, is formed.Thicknesses of the first plating layer and the second plating layer ofthe plating layer stacked body are smaller than a thickness of theplating layer stacked body, and a strong adhesion layer is previouslyformed when baking the first plating layer. Accordingly, it is possibleto suppress the peeling off due to a stress of the second plating layergenerated when baking the second plating layer, as compared to a case ofbaking a plating layer having the same thickness as that of the platinglayer stacked body. Therefore, the adhesivity between the underlyinglayer and the first plating layer and the second plating layer can beenhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a plating system in accordancewith an example embodiment.

FIG. 2 is a flowchart for describing a plating method in accordance withthe example embodiment.

FIG. 3A to FIG. 3F are diagrams illustrating a substrate on which theplating method of the example embodiment is performed.

FIG. 4 is a cross sectional view illustrating a plating layer stackedbody as a Cu diffusion barrier film.

FIG. 5 is a side cross sectional view illustrating a plating layerforming unit.

FIG. 6 is a plane view illustrating the plating layer forming unit.

FIG. 7 is a side cross sectional view illustrating a plating layerbaking unit.

FIG. 8 is a cross sectional view showing a plating layer stacked body asa seed film, which is illustrated as a modification example of theexample embodiment.

DETAILED DESCRIPTION

Plating System

Referring to FIG. 1 to FIG. 7, an example embodiment will be described.

First, a plating system in accordance with the example embodiment willbe elaborated with reference to FIG. 1.

As depicted in FIG. 1, the plating system 10 is configured to perform aplating process on a substrate (silicon substrate) 2, such as asemiconductor wafer, having a recess 2 a.

The plating system 10 includes a cassette station 18 configured to mountthereon a cassette (not shown) which accommodates the substrate 2; asubstrate transfer arm 11 configured to take out the substrate 2 fromthe cassette on the cassette station 18 and transfer the substrate 2;and a moving path 11 a along which the substrate transfer arm 11 ismoved.

Arranged at one side of the moving path 11 a are an adhesion layerforming unit 12 configured to form an adhesion layer 21 to be describedlater by adsorbing a coupling agent such as a silane coupling agent ontothe substrate 2; a catalyst adsorption layer forming unit 13 configuredto form a catalyst adsorption layer 22 to be described later byadsorbing a catalyst onto the adhesion layer 21 of the substrate; and aplating layer forming unit 14 configured to form plating layers 23 a and23 b serving as a Cu diffusion barrier film (barrier film) to bedescribed later on the catalyst adsorption layer 22 of the substrate 2.

Further, arranged at the other side of the moving path 11 a are aplating layer baking unit 15 configured to bake the plating layers 23 aand 23 b formed on the substrate 2; and an electroless Cu plating layerforming unit 16 configured to form an electroless copper (Cu) platinglayer 24, serving as a seed film to be described later, on the platinglayers 23 a and 23 b formed on the substrate 2.

Further, an electrolytic Cu plating layer forming unit 17 configured tofill the recess 2 a of the substrate 2 with an electrolytic Cu platinglayer 25 while using the electroless Cu plating layer 24 as a seed filmis provided adjacent to the plating layer baking unit 15.

After the first plating layer 23 a is formed in the plating layerforming unit 14, the first plating layer 23 a is baked in the platinglayer baking unit 15. Then, in the plating layer forming unit 14, thesecond plating layer 23 b is formed on top of the baked first platinglayer 23 a, and the second plating layer 23 b is then baked in theplating layer baking unit 15.

Through these processes, the plating layer stacked body 23 in which thefirst plating layer 23 a and the second plating layer 23 b are stackedis formed on the catalyst adsorption layer 22 of the substrate 2.

Each of the first plating layer 23 a and the second plating layer 23 bof the plating layer stacked body 23 having the above-describedstructure serves as a Cu diffusion barrier film (barrier film).

Further, the respective constituent components of the above-describedplating system, for example, the cassette station 18, the substratetransfer arm 11, the adhesion layer forming unit 12, the catalystadsorption layer forming unit 13, the plating layer forming unit 14, theplating layer baking unit 15, the electroless Cu plating layer formingunit 16 and the electrolytic Cu plating layer forming unit 17 arecontrolled by a controller 19 according to various types of programsrecorded in a storage medium 19A provided in the controller 19, so thatvarious processes are performed on the substrate 2. Here, the storagemedium 19A stores thereon various kinds of setup data or various kindsof programs such as a plating method to be described later. The storagemedium 19A may be implemented by a computer-readable memory such as aROM or a RAM, or a disk-type storage medium such as a hard disk, aCD-ROM, a DVD-ROM or a flexible disk, as commonly known in the art.

Below, the plating layer forming unit 14 and the plating layer bakingunit 15 configured to form the first plating layer 23 a and the secondplating layer 23 b, which serve as the Cu diffusion barrier film(barrier film), and the electroless Cu plating layer forming unit 16will be further elaborated.

Among these, each of the plating layer forming unit 14 and theelectroless Cu plating layer forming unit 16 may be implemented by aplating apparatus as illustrated in FIG. 5 and FIG. 6.

These plating apparatuses 14 and 16 are as depicted in FIG. 5 and FIG.6.

That is, each of the plating apparatuses 14 and 16 includes, as shown inFIG. 5 and FIG. 6, a substrate holding/rotating device (substrateaccommodating unit) 110 configured to hold and rotate the substrate 2within a casing 101; liquid supplying devices 30 and 90 configured tosupply a plating liquid, a cleaning liquid or the like onto a surface ofthe substrate 2; a cup 105 configured to collect the plating liquid, thecleaning liquid or the like dispersed from the substrate 2; drainingopenings 124, 129 and 134 configured to drain the plating liquid or thecleaning liquid collected by the cup 105; liquid draining devices 120,125 and 130 configured to drain the liquids collected in the drainingopenings; and a controller 160 configured to control the substrateholding/rotating device 110, the liquid supplying devices 30 and 90, thecup 105 and the liquid draining devices 120, 125 and 130.

(Substrate Holding/Rotating Device)

The substrate holding/rotating device 110 includes, as illustrated inFIG. 5 and FIG. 6, a hollow cylindrical rotation shaft 111 verticallyextended within the casing 101; a turntable 112 provided on an upper endportion of the rotation shaft 111; a wafer chuck 113 disposed on aperipheral portion of a top surface of the turntable 112 to support thesubstrate 2; and a rotating device 162 configured to rotate the rotationshaft 111. The rotating device 162 is controlled by the controller 160,and the rotation shaft 111 is rotated by the rotating device 162. As aresult, the substrate 2 supported on the wafer chuck 113 is rotated.

(Liquid Supplying Device)

Now, the liquid supplying devices 30 and 90 configured to supply aplating liquid, a cleaning liquid, or the like onto the surface of thesubstrate 2 will be explained with reference to FIG. 5 and FIG. 6. Theliquid supplying device 30 is a plating liquid supplying deviceconfigured to supply a plating liquid for performing a plating processon the surface of the substrate 2. The liquid supplying device 90 is acleaning liquid supplying device configured to supply a cleaning liquidonto the surface of the substrate 2.

As depicted in FIG. 5 and FIG. 6, a discharge nozzle 32 is provided at anozzle head 104. The nozzle head 104 is provided at a leading endportion of an arm 103. The arm 103 is provided at a supporting shaft 102rotated by a rotating device 165 to be moved in a vertical direction. Aplating liquid supplying line of the plating liquid supplying device 30is embedded within the arm 103. With this configuration, it is possibleto discharge the plating liquid onto a target position on the surface ofthe substrate 2 through the discharge nozzle 32 from a required supplyheight.

(Cleaning Liquid Supplying Device 90)

The cleaning liquid supplying device 90 is configured to perform acleaning process on the substrate 2 as will be described later. Asillustrated in FIG. 5, the cleaning liquid supplying device 90 includesa nozzle 92 provided at the nozzle head 104. In this configuration,either a cleaning liquid or a rinse liquid is selectively dischargedonto the surface of the substrate 2 from the nozzle 92.

(Liquid Draining Device)

Now, the liquid draining devices 120, 125 and 130 configured to drainout the plating liquid or the cleaning liquid dispersed from thesubstrate 2 will be elaborated with reference to FIG. 5. As shown inFIG. 5, the cup 105, which can be moved up and down by an elevatingdevice 164 and has the draining openings 124, 129 and 134, is disposedwithin the casing 101. The liquid draining devices 120, 125 and 130 areconfigured to drain out the liquids collected in the draining openings124, 129 and 134, respectively.

As depicted in FIG. 5, the plating liquid draining devices 120 and 125include collecting flow paths 122 and 127 and waste flow paths 123 and128, which are switched by flow path switching devices 121 and 126,respectively. Here, the plating liquid is collected and reused throughthe collecting flow paths 122 and 127, while the plating liquid isdrained out through the waste flow paths 123 and 128. Further, as shownin FIG. 5, the processing liquid draining device 130 is only equippedwith a waste flow path 133.

Further, as depicted in FIG. 5 and FIG. 6, the collecting flow path 122of the plating liquid draining device 120 configured to drain theplating liquid is connected to an outlet side of the substrateaccommodating unit 110, and a cooling buffer 120A configured to cool theplating liquid is provided at a portion of the collecting flow path 122in the vicinity of the outlet side of the substrate accommodating unit110.

Now, the plating layer baking unit 15 will be elaborated.

The plating layer baking unit 15 includes, as illustrated in FIG. 7, anairtightly sealed casing 15 a; and a hot plate 15A provided within theairtightly sealed casing 15 a.

The airtightly sealed casing 15 a of the plating layer baking unit 15 isprovided with a transfer opening (not shown) through which the substrate2 is transferred. An N₂ gas is supplied into the airtightly sealedcasing 15 a through an N₂ gas supply opening 15 c.

Concurrently, the inside of the airtightly sealed casing 15 a isevacuated through an exhaust opening 15 b, and by supplying the N₂ gasinto the airtightly sealed casing 15 a, the inside of the airtightlysealed casing 15 a can be maintained under an inert gas atmosphere.

An operation of the example embodiment having the above-describedconfiguration will be explained with reference to FIG. 2 to FIG. 3F.

First, in a pre-process, a recess 2 a is formed on a substrate (siliconsubstrate) 2 such as a semiconductor wafer or the like. The substrate 2having thereon the recess 2 a is then transferred into the platingsystem 10 in accordance with the example embodiment.

Within the adhesion layer forming unit 12 of the plating system 10, anadhesion layer 21 is formed on the substrate 2 having the recess 2 a(FIG. 2 and FIG. 3A).

Here, as a method of forming the recess 2 a on the substrate 2, acommonly known method in the art may be appropriately employed.Specifically, as a dry etching technique, for example, a general-purposetechnique using a fluorine-based gas or a chlorine-based gas may beemployed. Especially, in order to form a hole having a high aspect ratio(a hole depth/a hole diameter), a method using an ICP-RIE (InductivelyCoupled Plasma Reactive Ion Etching) technique, which can perform a deepetching process with a high speed, may be more appropriately adopted.Especially, a Bosch process in which an etching process using sulfurhexafluoride (SF₆) and a protection process using a teflon-based gassuch as C₄F₈ are repeatedly performed may be appropriately utilized.

Further, the adhesion layer forming unit 12 has a decompression chamber(not shown) equipped with a heating unit. Within the adhesion layerforming unit 12, a coupling agent such as a silane coupling agent isadsorbed onto the substrate 2 having the recess 2 a, so that theadhesion layer 21 is formed on the substrate 2 (SAM process). Theadhesion layer 21 formed by adsorbing the silane coupling agent isconfigured to improve adhesivity between the substrate 2 and a catalystadsorption layer 22 to be described later.

The substrate 2 on which the adhesion layer 21 is formed in the adhesionlayer forming unit 12 is then transferred into the catalyst adsorptionlayer forming unit 13 by the substrate transfer arm 11. In the catalystadsorption layer forming unit 13, Pd ions that may serve as a catalystare adsorbed on the adhesion layer 21 of the substrate 2, so that thecatalyst adsorption layer 22 is formed (FIG. 3B).

As the catalyst adsorbing process, a process of discharging an aqueoussolution of palladium chloride through a nozzle and adsorbing Pd ionsserving as the catalyst onto the surface of the substrate 2 may beemployed. To elaborate, tin ions are adsorbed onto the surface of thesubstrate 2 by discharging a stannous chloride solution onto thesubstrate 2, and, then, by discharging the palladium chloride solutiononto the surface 2 to replace the tin ions, the Pd ions are adsorbedonto the substrate 2. Then, by discharging sodium hydroxide onto thesubstrate 2, the tin ions remaining on the substrate 2 are removed.

After the catalyst adsorption layer 22 is formed on the substrate 2 inthe catalyst adsorption layer forming unit 13 as stated above, thesubstrate 2 is then transferred into the plating layer forming unit 14by the substrate transfer arm 11.

Subsequently, in the plating layer forming unit 14, a first platinglayer 23 a serving as a Cu diffusion barrier film (barrier film) isformed on the catalyst adsorption layer 22 of the substrate 2 (FIG. 3Cand FIG. 4).

In this case, the plating layer forming unit 14 is implemented by theplating apparatus as illustrated in FIG. 5 and FIG. 6. The first platinglayer 23 a can be formed by performing an electroless plating process onthe catalyst adsorption layer 22 of the substrate 2.

When forming the first plating layer in the plating layer forming unit14, a plating liquid containing, for example, Co—W—B may be used, and atemperature of the plating liquid is maintained at 40° C. to 75° C.(desirably, 65° C.).

By supplying the plating liquid containing the Co—W—B onto the substrate2, the first plating layer 23 a containing the Co—W—B is formed on thecatalyst adsorption layer 22 of the substrate 2 through the electrolessplating process.

Thereafter, the substrate 2 in which the first plating layer 23 a isformed on the catalyst adsorption layer 22 is transferred from theplating layer forming unit 14 into the airtightly sealed casing 15 a ofthe plating layer baking unit 15 by the substrate transfer arm 11.Within the airtightly sealed casing 15 a of the plating layer bakingunit 15, the substrate 2 is heated on the hot plate 15A under an inertgas atmosphere of N₂ gas in order to suppress the substrate 2 from beingoxidized. Accordingly, the first plating layer 23 a of the substrate 2is baked (baking process).

When baking the first plating layer 23 a in the plating layer bakingunit 15, a baking temperature may be set to be in the range from, e.g.,150° C. to 200° C., and a baking time is set to be in the range from,e.g., 10 minutes to 30 minutes.

By baking the first plating layer 23 a on the substrate 2 as describedabove, moisture within the first plating layer 23 a can be removed, and,at the same time, the bond between metals within the first plating layer23 a can be enhanced. The substrate 2 heated in the plating layer bakingunit 15 is delivered back to the plating layer forming unit 14 by thesubstrate transfer arm 11. Then, within the plating layer forming unit14, an electroless plating process is performed on the substrate 2.Accordingly, the second plating layer 23 b is formed on the firstplating layer 23 a through the autocatalytic plating.

When forming the second plating layer 23 b on the first plating layer 23a, a plating liquid containing Co—W—B may be used, as in the case offorming the first plating layer 23 a. A temperature of the platingliquid is maintained at 40° C. to 75° C. (desirably, 65° C.), as in thecase of forming the first plating layer 23 a.

Alternatively, when forming the second plating layer 23 b in the platinglayer forming unit 14, unlike when forming the first plating layer 23 a,a plating liquid containing Co—W—P may be used instead of the platingliquid containing the Co—W—B, and a temperature of the plating liquidmay be in the range from, e.g., 40° C. to 80° C., desirably, 70° C.

In any cases, when forming the second plating layer 23 b, a platingliquid containing the same metals (Co—W) as the first plating layer 23 ais used, and the second plating layer 23 b formed as described aboveserves as a Cu diffusion barrier film (barrier film).

Further, in the above, though the plating liquids containing the Co—Ware used when forming the first plating layer 23 a and the secondplating layer 23 b, the example embodiment may not be limited thereto.By way of example, a plating liquid containing Co may be used to formthe first plating layer 23 a, while using a plating liquid containingCo—W to form the second plating layer 23 b. Alternatively, a platingliquid containing Co—W may be used to form the first plating layer 23 a,while using a plating liquid containing Co to form the second platinglayer 23 b. A combination of a plating liquid for forming the firstplating layer 23 a and a plating liquid for forming the plating liquidfor forming the second plating layer 23 b can be selected among any ofplating liquids containing cobalt-based materials, e.g., a Co—Pcontaining plating liquid, a Co—B containing plating liquid, a Co—Wcontaining liquid, a Co—W—P containing plating liquid, a Co—W—Bcontaining plating liquid, and so forth.

Subsequently, the substrate 2 on which the second plating layer 23 b isformed in the plating layer forming unit 14 is delivered back to theplating layer baking unit 15 from the plating layer forming unit 14 bythe substrate transfer arm 11. The substrate 2 is heated on the hotplate 15A within the airtightly sealed casing 15 a of the plating layerbaking unit 15, so that the second plating layer 23 b is baked.

A baking temperature and a baking time for baking the second platinglayer 23 b are set to be the substantially same as the bakingtemperature and the baking time for baking the first plating layer 23 a.However, the baking temperature and the baking time for the secondplating layer 23 b may be set to be different from the bakingtemperature and the baking time for the first plating layer 23 a. Bybaking the second plating layer 23 b on the substrate 2, moisture withinthe second plating layer 23 b can be removed, and, at the same time, thebond between metals within the second plating layer 23 b can beenhanced.

Through the above-described processes, it is possible to obtain aplating layer stacked body 23 having the first plating layers 23 a andthe second plating layer 23 b and serving as a Cu diffusion barrier film(barrier film).

In general, although the bonds between the metals in the first platinglayer 23 a and the second plating layer 23 b can be enhanced by bakingthe plating layers 23 a and 23 b, if the thicknesses of the bakedplating layers are large, a stress accompanied by deformation of theplating layers may be generated between an underlying layer and theplating layers.

In accordance with the present example embodiment, however, the platinglayer stacked body 23 serving as the barrier film is formed of the firstplating layer 23 a obtained by the first plating layer forming processand the first plating layer baking process and the second plating layer23 b obtained by the second plating layer forming process and the secondplating layer baking process. Thus, the thickness of the plating layerbaked in the first baking process or in the second baking process can bemade small, as compared to the entire thickness of the plating layerstacked body 23.

Accordingly, when baking the respective plating layers 23 a and 23 b, astress generated between these layers and the underlying layer (forexample, the catalyst adsorption layer 22) can be decreased, so thatadhesivity between the plating layers 23 a and 23 b and the underlyinglayer can be increased.

Further, in order to enhance the adhesivity between the plating layers23 a and 23 b and the underlying layer 22 by reducing the stressgenerated therebetween, it may be desirable to set the thickness of thefirst plating layer 23 a to be smaller than the thickness of the secondplating layer 23 b. Further, in the baking processes of the platinglayers 23 a and 23 b, it is desirable to remove moisture sufficiently bysetting the baking temperature for the first plating layer 23 a to behigher than the baking temperature for the second plating layer 23 b orby setting the baking times for the first plating layer 23 a to belonger than the baking times for the second plating layer 23 b.

Further, the plating layer stacked body 23 may not be limited to thestructure including the first plating layer 23 a and the second platinglayer 23 b. For example, the plating layer stacked body 23 may include athird plating layer and a fourth plating layer in addition to the firstplating layer 23 a and the second plating layer 23 b.

The substrate 2 having the plating layer stacked body 23 serving as thebarrier film is then sent to the electroless Cu plating layer formingunit 16 by the substrate transfer arm 11.

Subsequently, in the electroless Cu plating layer forming unit 16, anelectroless Cu plating layer 24 serving as a seed film for forming anelectrolytic Cu plating layer 25 is formed on the plating layer stackedbody 23 of the substrate 2 (FIG. 3D).

Here, the electroless Cu plating layer forming unit 16 is implemented bythe plating apparatus as illustrated in FIG. 5 and FIG. 6. By performingthe electroless plating process on the plating layer stacked body 23 ofthe substrate 2, the electroless Cu plating layer 24 can be formed.

The electroless Cu plating layer 24 formed in the electroless Cu platinglayer forming unit 16 serves as the seed film for forming theelectrolytic Cu plating layer 25. A plating liquid used in theelectroless Cu plating layer forming unit 16 may contain a copper saltas a source of copper ions, such as copper sulfate, copper nitrate,copper chloride, copper bromide, copper oxide, copper hydroxide, copperpyrophosphate, or the like. The plating liquid may further contain areducing agent and a complexing agent for the copper ions. Further, theplating liquid may further contain various kinds of additives forimproving stability or speed of the plating reaction.

The substrate 2 on which the electroless Cu plating layer 24 is formedas described above is then sent to the electrolytic Cu plating layerforming unit 17 by the substrate transfer arm 11. Here, the substrate 2on which the electroless Cu plating layer 24 is formed may be sent tothe electrolytic Cu plating layer forming unit 17 after baked in thebaking unit 15. Subsequently, an electrolytic Cu plating process isperformed on the substrate 2 within the electrolytic Cu plating layerforming unit 17, so that the electrolytic Cu plating layer 25 is buriedwithin the recess 2 a of the substrate 2 while using the electroless Cuplating layer 24 as the seed film (FIG. 3E).

Thereafter, the substrate 2 is unloaded from the plating system 10, anda rear surface side of the substrate 2 (opposite side to the side wherethe recess 2 a is formed) is polished chemically and mechanically (FIG.3F).

In accordance with the present example embodiment as stated above, theplating layer stacked body 23 serving as the barrier film is formed ofthe first plating layer 23 a obtained by the first plating layer formingprocess and the first plating layer baking process and the secondplating layer 23 b obtained by the second plating layer forming processand the second plating layer baking process. Accordingly, a stressbetween these plating layers and the underlying layer generated whenbaking the plating layers 23 a and 23 b can be reduced, so thatadhesivity between the plating layers and the underlying layer can beenhanced.

Modification Examples

Now, modification examples of the example embodiment will be explained.In the above-described example embodiment, the plating layer stackedbody 23 serving as the Cu diffusion barrier film (barrier film) isformed of the first plating layer 23 a and the second plating layer 23b. However, the example embodiment may not be limited thereto, and theelectroless Cu plating layer 24 serving as the seed film may be formedof a plating layer stacked body 23 having a first plating layer 24 a anda second plating layer 24 b (FIG. 8).

In such a case, the first plating layer 24 a of the electroless Cuplating layer 24 is formed through a first plating layer forming processin the electroless Cu plating layer forming unit 16, and, then, bakedthrough a first plating layer baking process in the plating layer bakingunit 15. Further, the second plating layer 24 b is formed through asecond plating layer forming process in the electroless Cu plating layerforming unit 16 and, then, baked through a second plating layer bakingprocess in the plating layer baking unit 15. Accordingly, the platinglayer stacked body 24 having the first plating layer 24 a and the secondplating layer 24 b and serving as the seed film for the electrolytic Cuplating layer 25 is obtained.

Further, the above-described example embodiment has been described forthe case of burying the electrolytic Cu plating layer through theelectrolytic Cu plating process. However, the example embodiment may notbe limited thereto, and it may be possible to form the Cu plating layerthrough the electroless Cu plating process instead of the electrolyticCu plating process.

Additionally, in the above-described example embodiment, when baking thefirst plating layer 23 a and the second plating layer 23 b, thesubstrate 2 is heated on the hot plate 15A under the inert-gasatmosphere of N₂ gas within the airtightly sealed casing 15 a of theplating layer baking unit 15. However, the example embodiment may not belimited thereto, and the substrate 2 may be heated on the hot plate 15Aafter evacuating the inside of the airtightly sealed casing 15 a to avacuum level, for in order to lower the temperature or shorten theprocessing time.

Furthermore, in the above-described example embodiment, the platinglayer forming unit 14 and the plating baking unit 15 are configured asseparate apparatuses. However, the example embodiment may not be limitedthereto. By way of example, by providing a heating source such as a lampirradiator 200 (UV light or the like) above the substrate 2 or a hotplate (not shown) covering the substrate 2 in the plating layer formingunit 14 shown in FIG. 5, it may be possible to bake the plating layerswithin the plating layer forming unit 14.

EXPLANATION OF CODES

-   -   2: Substrate    -   2 a: Recess    -   10: Plating system    -   11: Substrate transfer arm    -   12: Adhesion layer forming unit    -   13: Catalyst adsorption layer forming unit    -   14: Plating layer forming unit    -   15: Plating layer baking unit    -   15A: Hot plate    -   15 a: Airtightly sealed casing    -   15 b: Exhaust opening    -   15 c: N₂ gas supply opening    -   16: Electroless Cu plating layer forming unit    -   17: Electrolytic Cu plating layer forming unit    -   18: Cassette station    -   19: Controller    -   19A: Storage medium    -   21: Adhesion layer    -   22: Catalyst adsorption layer    -   23: Plating layer stacked body    -   23 a: First plating layer    -   23 b: Second plating layer    -   24: Electroless Cu plating layer    -   25: Electrolytic Cu plating layer

We claim:
 1. A plating method of performing a plating process on asubstrate, the plating method comprising: a substrate preparing processof preparing the substrate; an adhesion layer forming process of formingan adhesion layer by adsorbing a coupling agent onto the substrate; acatalyst adsorption layer forming process of forming a catalystadsorption layer by adsorbing a catalyst onto the adhesion layer; and adiffusion barrier film forming process of forming a diffusion barrierfilm, as a plating layer stacked body, onto the catalyst adsorptionlayer; wherein the diffusion barrier film forming process comprises: afirst plating layer forming process of forming a first plating layer onthe catalyst adsorption layer by performing a plating process on thesubstrate; a first plating layer baking process of baking the firstplating layer by heating the substrate to enhance bond between metalswithin the first plating layer; a second plating layer forming processof forming a second plating layer on the first plating layer byperforming a plating process on the substrate; and a second platinglayer baking process of baking the second plating layer by heating thesubstrate to enhance bond between metals within the second platinglayer, wherein the first plating layer and the second plating layer formthe plating layer stacked body, and the plating layer stacked bodyfunctions as the diffusion barrier film, a thickness of the firstplating layer is set to be smaller than a thickness of the secondplating layer to enhance an adhesivity between the first and secondplating layers and the catalyst adsorption layer, and a bakingtemperature for the first plating layer is set to be higher than abaking temperature for the second plating layer, and a baking time forthe first plating layer is set to be longer than a baking time for thesecond plating layer.
 2. The plating method of claim 1, wherein each ofthe plating layers of the plating layer stacked body functions as a Cudiffusion barrier film.
 3. The plating method of claim 1, wherein thefirst plating layer of the plating layer stacked body is formed on thecatalyst adsorption layer, and the second plating layer of the platinglayer stacked body is formed on the first plating layer through aautocatalytic plating.
 4. The plating method of claim 1, wherein acomponent of the plating liquid in the first plating layer formingprocess is the same as in the second plating layer forming process. 5.The plating method of claim 1, wherein a component and a temperature ofthe plating liquid in the first plating layer forming process aredifferent from those in the second plating layer forming process.
 6. Theplating method of claim 1, wherein the plating layer baking process isperformed under an inert-gas atmosphere or a vacuum.